A kind of control method of centrifugal compressed air station system pressureTechnical field
The present invention relates to centrifugal compressed air stations to manage control field, the especially control of centrifugal compressed air station system pressure concentratedlyMethod and control system.
Background technique
Four kind fluid media (medium)s (water, compressed air, steam and natural of the compressed air as energy delivery in industrial productionOne of gas) because it is used widely the features such as safe, clean, easily-controllable, play in the industrial production very importantEffect.At present integrated mill and industrial park all establish air compression station carry out central gas supply, each air compression station generally by several veryTo more than ten or more air-compressor sets at, used air compressor machine type mainly has screw-rod air compressor and centrifugal air compressor,Middle centrifugal air compressor is increasingly widely applied in air compression station with its high-efficient and big feature of capacity.
It is more demanding to automatic control technology but since centrifugal air compressor has the inherent characteristics such as surge, especiallyThe operating condition big to air supply demand fluctuation for user should guarantee that user's supply gas pressure is stablized, make in air compression station againEach compressor undertakes reasonable load, reduces energy consumption, is a great challenge for the control of this kind of centrifugal compressed air station.
The main control mode of centrifugal compressed air station has at present:
(1) every centrifugal air compressor carries PLC control cabinet by machine, completes the basic control of air compressor machine, usually runsPersonnel are to the exit pressure levels of scene setting air compressor machine, and to adjust the output load of air compressor machine, the every unit in this scene is independentAdjusting is still control mode commonplace at present.
(2) on the basis of former mode, increase centralized control system, the prison to all air compressor machines in scene may be implementedDepending on, each unit in long-range start and stop scene, remote setting goal pressure etc..
The above control method is still that separate unit air compressor machine independently automatically adjusts and based on long-range or on-site manual intervenes, forThe multiple air compressors of operation simultaneously, act on strong air compressor machine and can make to act on weak air compressor machine and arrive first surge limit, and it is unnecessary to causeWaste of leaking informaton, under user's operating condition big to air supply demand fluctuation, single machine it is separately adjustable and it is manual intervention often ringThe external system pressure fluctuation of air compression station should be caused larger not in time.
Therefore it needs to invent a kind of air compression station system compress control method, both can control user's air supply system pressure and stablized,So that each compressor in air compression station is undertaken reasonable load again, reduces energy consumption.
Summary of the invention
Stablize to not only can control user's air supply system pressure, but also each compressor set in air compression station is made to undertake reasonable bearIt carries, reduces energy consumption, the invention proposes the control methods and control system of a kind of centrifugal compressed air station system pressure.
The present invention adopts the following technical scheme:
A kind of control method of centrifugal compressed air station system pressure, be related to centrifugal compressed air station output system pressure control withAnd each compressor set load compensation control in air compression station, including control system, the control system include centralized control system, instituteIt states centralized control system to be bi-directionally connected with compressor set scene PLC control station, the centralized control system includes that system pressure becomesChange compensating module, load compensation module and power limit control module, the pressure change compensating module computing system pressure to setDefinite value PSWith the exhaust system pressure P of pressure sensor detectiondPressure divergence change rate ecp, calculated by fuzzy controller defeatedPressure change offset P outC, the surge distance D of the load compensation module calculating compressor operating point to regulation line for surge, withAnd surge distance D and average surge distance DavgSurge deviation eD, fuzzy controller is according to surge deviation eDIt is inclined with surgeDifference change rate ecDCalculate output load offset PL, the power limit control module control pressure change offset PCWith it is negativeLotus offset PLOutput, the method is characterized in that: the system pressure setting value PS, pressure change offset PC, loadOffset PLSummation obtains remote pressure setting instruction Pds, the remote pressure setting instruction Pds=PS+PC+PL, will be described long-rangePressure setting instruction PdsScene PLC control station is inputted as set point, is preset according to compressor set power each in air compression stationPower limit value, judge whether each compressor transfinites, pass through the every compressor group of scene PLC control station control if transfinitingInlet guide vane and exhaust valve, it is ensured that every compressor group exports suitable load.
Preferably, the calculating pressure change offset PCThe step of it is as follows: (1) by pressure sensor detect centrifugationFormula air compression station exhaust system pressure PdWith default pressure value PSIt does absolute difference and pressure divergence e is calculatedp, pass through differentialDevice obtains pressure divergence change rate ecp；(2) to pressure divergence change rate ecpFuzzy processing is carried out, to pressure divergence change rateecpSet fuzzy subset are as follows: [NB, NS, ZR, PS, PB], to the output variable U of fuzzy algorithmic approachpThe fuzzy subset of setting are as follows: [NB,NS, ZR, PS, PB], fuzzy rule are as follows:
If(ecp is NB)then(Up is NB)
If(ecp is NS)then(Up is NS)
If(ecp is ZR)then(Up is ZR)
If(ecp is PS)then(Up is PS)
If(ecp is PB)then(Up is PB)
Selected pressure divergence change rate scale factor kecpWith output-scale-factor kup, by fuzzy controller operation, obtainPressure change compensating instruction PC。
Preferably, the calculated load offset PLThe step of it is as follows: (1) driving motor is detected by current sensorActual motion electric current Iop, a certain pressure at expulsion P ' is obtained by the surge curve of compressordUnder corresponding surge electric current ISL, meterCalculation obtains surge distance D:(2) average surge distance D is calculatedavg: Davg=∑ (D1、D2、…、Di)；It (3) will be eachThe surge distance D of compressor and average surge distance DavgCompare, obtains corresponding surge deviation eD, further calculate to obtainSurge deviation change rate ecD, to surge deviation eDWith surge deviation change rate ecDFuzzy processing is carried out, mould is passed throughLoad compensation value P is calculated in fuzzy controllersL。
Preferably, compressor operates in safety zone as surge distance D > 0；As surge distance D < 0, compressionMachine operates in unstable region.
Preferably, described to surge deviation eDWith surge deviation change rate ecDThe step of carrying out Fuzzy processing is such asUnder: (2) are to surge deviation eDSet fuzzy subset are as follows: [NB, NS, ZR, PS, PB], surge deviation change rate ecDSet mouldPaste subset are as follows: [NB, NS, ZR, PS, PB], to the output variable U of fuzzy algorithmic approachLSet fuzzy subset are as follows: [NB, NS, ZR, PS,PB]；(2) surge deviation scale factor k is selectedel, surge deviation change rate scale factor keclWith output-scale-factor kul。
Preferably, the power limit control module is according to the preset power threshold of each compressor set, judgementWhether each compressor set load transfinites, and pressure change offset P is limited if transfinitingCWith load compensation value PLOutput.
It is a kind of by the above method realize centrifugal compressed air station system pressure control control system, including control system andCompressor set, the control system include centralized control system, the compressor set be it is a plurality of, the compressor set includes existingField PLC control station, the scene PLC control station are bi-directionally connected with the centralized control system, and the centralized control system includesSystem pressure compensating for variations module, load compensation module and power limit control module, the system pressure compensating for variations moduleIncluding adder, differentiator and fuzzy controller, the load compensation module includes divider, averager, adder, differentiatorAnd fuzzy controller, the system pressure compensating for variations module, the load compensation module output end with the power poleControl module connection is limited, the output end of the power limit control module is connect with the scene PLC control station.
Preferably, the compressor set further includes compressor body, driving motor, current sensor, exhaust branch pipe, rowAir valve, check-valves and branch pipe pressure sensor, the driving motor output end connect compressor ontology, the current sensor withThe driving motor connection, the compressor body suction side are provided with inlet guide vane, the exhaust branch pipe and compressor bodyOutput end connection, the exhaust branch pipe side are disposed with branch pipe pressure sensor, exhaust valve and check-valves, and the electric current passesSensor, inlet guide vane, branch pipe pressure sensor connect control with the scene PLC control station with exhaust valve.
Preferably, the exhaust branch pipe of the compressor body connects an exhaust main pipe, the exhaust main pipe setting jointlyThere is pressure sensor, the pressure sensor connect control with the scene PLC control station.
The beneficial effects of the present invention are: (1), when system pressure change of error is larger, pressure change compensating module calculates systemThe deviation variation rate for the pressure set points and value of feedback of uniting calculates output pressure compensating for variations value by fuzzy controller, before thisFeed voltage power compensating for variations value enhances the system pressure self-regulation effect of live PLC control station, reduces system pressure and fluctuates modelIt encloses, system pressure is maintained to stablize；(2) in the balanced air compression station of load compensation feedforward action each unit load, avoid acting on weakAir compressor machine enter surge emptying state, cause energy waste；(3) when air compressor machine power reaches preset power limit, functionRate limit control module will limit pressure change compensation and load compensation control output, to avoid invalid output.
Detailed description of the invention
Fig. 1 is the ideograph for more centrifugal air compressor compressibilities being connected in parallel in the present invention；
Fig. 2 is a kind of control block diagram of centrifugal compressed air station system pressure in the present invention；
Fig. 3 is centrifugal compressor Anti-surge Control performance plot in the present invention.
In Fig. 1-3: 10, compressor body, 11, driving motor, 12, inlet guide vane, 13, exhaust valve, 14, check-valves, 15,Air inlet pipeline, 16, exhaust branch pipe, 17, scene PLC control station, 18, current sensor, 19, branch pipe pressure sensor, 20, outputSignal wire, 21, input signal cable, 22, pressure sensor, 23, exhaust main pipe, 24, centralized control system, 25, system pressure changeChange compensating module, 250, first adder, the 251, first differentiator, the 252, first fuzzy controller, 26, load compensation module,260, divider, 261, second adder, 262, averager, 263, third adder, the 264, second differentiator, the 265, second mouldFuzzy controllers, the 27, the 4th adder, 28, power limit control module, 29, fifth adder, 30, surge curve, 31, surgePoint, 32, actual motion point.
Specific embodiment
Below by specific embodiment, and in conjunction with attached drawing, technical scheme of the present invention is further described:
Embodiment: being as shown in Fig. 1 the mode for more centrifugal air compressor compressibilities being connected in parallel in the present inventionFigure, shown in be connected in parallel compressor set A, B ..., I, by the live PLC of centralized control system 24 and each compressor set controlIt stands 17 controls, part of compressor set capacity may be different, but the structure type of each compressor set is identical (complete in the present embodimentPortion is by taking motor-driven compressor form as an example), composition having the same, compressor set include scene PLC control station 17,Compressor body 10, driving motor 11, current sensor 18, exhaust branch pipe 16, exhaust valve 13, check-valves 14 and branch pipe pressure passSensor 19, the 11 output end connect compressor ontology 10 of driving motor, the current sensor 18 and the driving motor 11Connection, 10 suction side of compressor body are provided with inlet guide vane 12, and the exhaust branch pipe 16 is exported with compressor body 10End connection, 16 side of exhaust branch pipe is disposed with branch pipe pressure sensor 19, exhaust valve 13 and check-valves 14, the electricityFlow sensor 18, inlet guide vane 12, branch pipe pressure sensor 19 connect control with the scene PLC control station 17 with exhaust valve 13System, live PLC control station 17 are bi-directionally connected with 24 system of centralized control, and compressor body 10 sucks air from air inlet pipeline 15,Suction side is provided with inlet guide vane 12, and adjustment is drawn into the work gas scale of compressor body 10, and inlet guide vane 12 is by live PLCThe guide vane opening that control station 17 exports instructs control.
Compressor body 10 is driven by driving motor 11, and the electric current of driving motor 11 is detected by sensor 18, and is sent to existingField PLC control station 17 calculates, and the discharge side of compressor body 10 connects exhaust branch pipe 16, is furnished with branch pipe pressure on exhaust branch pipe 16Sensor 19, the branch pipe pressure at expulsion that will test are sent to live PLC control station 17 and calculate, and install exhaust valve in downstream branch13, compressor gas is discharged to atmosphere, arranged by the valve seat opening instruction control that exhaust valve 13 is exported by PLC field control station 17It is also equipped with check-valves 14 on gas branch pipe 16, connects an exhaust main pipe 23 jointly in the downstream side exhaust branch pipe 16 of check-valves 14,The compressed gas of each compressor set A, B ... I discharge is concentrated through exhaust main pipe 23 and compressor gas is sent to user's use, compressionThe exhaust system pressure P of systemdIt is detected by pressure sensor 22, the signal detected is sent to the scene of each compressor set respectivelyPLC control station 17 and centralized control system 24.
All signals that live PLC control station 17 will test are sent to collection in a communication manner, by output signal line 23Remote pressure is set instruction P by middle control system 50, centralized control system 50dsLive PLC control is sent to by input signal cable 24System station 20.
As shown in Fig. 2 it is a kind of control block diagram of centrifugal compressed air station system pressure, is related to centrifugal compressed air station outputEach compressor set load compensation control in system pressure control and air compression station, mainly by centralized control system 24 and scene PLCControl station 17 is completed, and wherein centralized control system 24 completes the calculating of system pressure instruction, and live PLC control station 17 is then with collectionThe remote pressure setting instruction P that middle control system 24 exportsdsFor set point, inlet guide vane 12 and the row of every compressor group are controlledAir valve 13, so that every compressor group exports suitable load.
It is as shown in Fig. 3 centrifugal compressor Anti-surge Control performance plot, for motor-driven compressor, performance plotMiddle abscissa is the electric current of driving motor 11, and ordinate is the pressure at expulsion of compressor set, and preset surge curve 30 canThe characteristic curve or live actual tests provided according to producer obtains, in a certain pressure at expulsion P 'dUnder pumping point 31, correspond toElectric current ISLFor surge electric current, the corresponding actual current I of compressor actual motion point 32OP。
Centralized control system 24 includes system pressure compensating for variations module 25, load compensation module 26 and power limit controlModule 28, the system pressure compensating for variations module 25 include first adder 250, the first differentiator 251 and the first Fuzzy ControlDevice 252 processed, the load compensation module 26 include divider 260, averager 261, second adder 262, third adder263, the second differentiator 264 and the second fuzzy controller 265, the system pressure compensating for variations module 25, load compensation module26 output end is connect with the power limit control module 28, the output end of the power limit control module 28 and scenePLC control station 17 connects, 25 computing system pressure set points P of system pressure compensating for variations moduleSIt is detected with pressure sensor 22Exhaust system pressure PdPressure divergence change rate ecp, output pressure compensating for variations is calculated by the first fuzzy controller 252Value PC, the system pressure setting value PSIt is set according to pressure requirements of the user to required compressed gas by operator, in user coupleUnder the big operating condition of air supply demand fluctuation, original system pressure setting control cannot adjust in time, real system pressureFluctuate it is larger, therefore according to actual pressure situation of change calculate pressure change offset PC, to improve control intensity, the calculatingPressure change offset PCThe step of it is as follows:
(1) the centrifugal compressed air station exhaust system pressure P detected by pressure sensor 22dWith default pressure value PSIt is logicalIt crosses first adder 250 and does absolute difference and pressure divergence e is calculatedp, pressure divergence variation is obtained by the first differentiator 251Rate ecp；
(2) to pressure divergence change rate ecpFuzzy processing is carried out, to pressure divergence change rate ecpSet fuzzy subsetAre as follows: [NB, NS, ZR, PS, PB], to the output variable U of fuzzy algorithmic approachpThe fuzzy subset of setting are as follows: [NB, NS, ZR, PS, PB],Fuzzy rule are as follows:
If(ecp is NB)then(Up is NB)
If(ecp is NS)then(Up is NS)
If(ecp is ZR)then(Up is ZR)
If(ecp is PS)then(Up is PS)
If(ecp is PB)then(Up is PB)
Selected pressure divergence change rate scale factor kecpWith output-scale-factor kup, pass through the first fuzzy controller 252Operation obtains pressure change compensating instruction PC, it is sent to the 4th adder 27.
The load compensation module 26 calculate compressor operating point to surge curve 30 surge distance D and surge away fromFrom D and average surge distance DavgSurge deviation eD, the second fuzzy controller 265 is according to surge deviation eDWith surge deviationIt is worth change rate ecDCalculate output load offset PL, the calculated load offset PLThe step of it is as follows:
(1) the actual motion electric current I of driving motor 11 is detected by current sensor 18op, bent by the surge of compressorLine 30 obtains a certain pressure at expulsion P 'dUnder corresponding surge electric current ISL, surge distance is calculated by divider 260
(2) average surge distance D is calculated by second adder 262, averager 261avg: Davg=∑ (D1、D2、…、Di)；
(3) by the surge distance D of each compressor and average surge distance DavgDifference is carried out in input third adder 263Compare, obtains corresponding surge deviation eD, further import in the second differentiator 264 and surge deviation change rate be calculatedecD, to surge deviation eDWith surge deviation change rate ecDFuzzy processing is carried out, is counted by the second fuzzy controller 265Calculation obtains load compensation value PL, it is sent to the 4th adder 27.
It is described to surge deviation eDWith surge deviation change rate ecDThe step of carrying out Fuzzy processing is as follows: (2) are rightSurge deviation eDSet fuzzy subset are as follows: [NB, NS, ZR, PS, PB], surge deviation change rate ecDSet fuzzy subset are as follows:[NB, NS, ZR, PS, PB], to the output variable U of fuzzy algorithmic approachLSet fuzzy subset are as follows: [NB, NS, ZR, PS, PB]；(2) it selectsDingchuan vibration deviation scale factor kel, surge deviation change rate scale factor keclWith output-scale-factor kul。
Its characteristic curve of the compressor set of different capabilities is different, and even identical compressor set, characteristic curve also hasMay be different, it acts on strong compressor and can make to act on weak compressor and first reach surge limit, open its exhaust valve 13, causeUnnecessary waste of leaking informaton.Pass through load compensation value PL, the reality output load of each compressor set can be balanced, more excellent effect is reachedThe effect of rate operation.
The pressure change offset PC, load compensation value PLIt send into the 4th adder 27 after summing by the power poleIt limits control module 28 and controls pressure change offset PCWith load compensation value PLOutput, the power limit control module 28Output end, system pressure setting value PSIt is connect with 29 input terminal of fifth adder, the system pressure setting value PS, pressure becomeChange offset PC, load compensation value PLSummation obtains remote pressure setting instruction P in fifth adder 29ds, the long-range pressurePower setting instruction is Pds=PS+PC+PL, the remote pressure is set into instruction PdsScene PLC control station is inputted as settingPoint, according to the preset power limit value of compressor set power each in air compression station, the power limit control module 28 judgesWhether each compressor transfinites, and power limit control module 28 limits pressure change offset P if transfinitingCWith load compensation valuePLOutput, and output signals to inlet guide vane 12 and exhaust valve 13 that live PLC control station 17 controls every compressor group, reallyIt protects every compressor group and exports suitable load.
Above-mentioned embodiment is only a preferred solution of the present invention, not the present invention is made in any formLimitation, there are also other variations and modifications on the premise of not exceeding the technical scheme recorded in the claims.